6.3 Basics of Reverse-Engineering Art
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Fig. 6.11 Nine-layer printed
circuit board of a cellphone,
disassembled by layers [5]
Functioning analysis includes detailed system description of operation timing
diagrams. The analytical system can be equipped with special testers wherever necessary (Fig. 6.12). Microprobe stations are usually used on the chip to track signals
of all levels. Sometimes, special testing packages are designed; in order to ensure
operation of the system in its actual functional modes, corresponding test signals of
actions are formed. Organization of effective system management and collection of
results are provided by input generators, logic analyzers, and oscilloscopes. After
that, all digital and analog signals and the system as a whole are analyzed. Using
a cellphone as an example once again, it needs to be said that this phone can be
partially disassembled but still electrically connected in order to keep working.
In order to monitor the most important key buses, chip pins, and connectors,
special probes are used. After that, the phone can keep working, while all received
signals will be analyzed by specialists in detail in order for them to understand all
subtleties of its operation.